Abstract
The design and performance of a WR-5 band 135–150-GHz Schottky diode-based frequency tripler which uses waveguide resonator filters for low loss impedance matching is presented in this paper. The filters used in this paper provide filtering, impedance matching, and microstrip (MS) to waveguide transitions in one structure. The matching optimization is achieved by scaling the external quality factors and adjusting the resonance frequency of the filter cavities. This approach transfers most of the tripler’s matching networks from MS circuitry to lower loss rectangular waveguide resonators. This is desirable and useful in particular for submillimeter wave and terahertz frequencies. The device presented is a 47.5 to 142.5 GHz bias-less frequency tripler with a 15-GHz output bandwidth. The tripler was measured to have a conversion loss of 13.1–14 dB across the band, at an input power of 17 dBm. The measured $S_{11}$ at the input port is better than 15 dB and all the reflection zeros from the filter resonances are distinct. The good agreement between measurements and simulations verifies the accuracy of the filter-based design approach.
Highlights
F ILTERS and impedance matching networks are fundamental microwave circuit elements
To the best of the authors’ knowledge, this paper reports, for the first time, comprehensive design approach towards high quality factor (Qu) filters integrated with a high-frequency active device
The approach discussed here improves the performance of the system by reducing the component count and achieves a lower insertion loss due to the use of high Qu waveguide resonators
Summary
F ILTERS and impedance matching networks are fundamental microwave circuit elements. The conventional approach is to design filters and matching networks separately, and to combine them in series to fulfill the design requirement(s). Examples of filters constructed by lumped LC components with integrated impedance matching functions can be found in [3] and [4] These studies are based on coupled planar transmission lines or lumped components, so the methods cannot be used in applications where the components are not planar or distributed (e.g., waveguides) or, as in our work, a mixture of both. With this design, the input and output of the diodes are coupled to the third and the sixth resonators.
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